1. Field of the Invention
The present invention relates to pet foods and to their methods of preparation. More particularly, the present invention relates to dried, shelf stable, high meat content jerky pet treats and to their extruder cooking methods of preparation.
2. Background of the Invention
Pet foods generally fall into four classes. First are the low moisture containing animal foods, i.e., animal foods containing less than about 15% by weight moisture, which are known as the dry pet foods and which are shelf stable because the water activity (0.2 to 0.4) therein does not lend itself to mold and bacterial growth. These products need not be aseptically canned or preserved since they are stable by their chemical characteristics. Typically, these products comprise extruder cooked, expanded cereal compositions occasionally containing meat by-products primarily for flavoring.
Second are the high moisture containing pet foods, i.e., having about 85% by weight moisture, and which require aseptic canning for preservation. These are the well known canned pet foods.
Third, in recent years the pet food industry has moved toward the very popular semi-moist or intermediate moisture pet foods. These pet foods are intermediate in moisture having a moisture content of from about 20% to 40%. The products are intended, generally, to resemble fresh meat or cooked meat. Thus, the products are generally characterized by a soft, crumbly texture and densities comparable to meat. While their moisture content would normally render the product susceptible to mold and bacterial growth, these products have been rendered stable by inclusion of various acids and solutes thereby altering the pH and also decreasing the water activity ("A.sub.w ") to a level which prevents mold and bacterial growth. Beginning with the Burgess patent, U.S. Pat. No. 3,202,514, the pet food industry has developed a multitude of methods for making semi-moist food products and rendering them stable against mold and bacterial growth. Generally, however, these products have always utilized a pH control and solute content in order to provide a critical acidity and water activity and thereby discourage mold and bacterial growth.
The fourth category of pet foods are meat treats. Meat treats for pets are well known pet food items. Pet dry meat treats or "pet jerky" are distinguished from conventional dry pet foods both compositionally and in method of preparation. Pet jerky products are conventionally prepared in a process comparable to jerky preparations for human consumption although cheaper grade meat starting materials are employed. Typically, various meat materials are first ground and admixed with spice blends and preservatives. The blends are then formed into extrudate ropes using a common forming extruder without cooking the meat. Thereafter, the meat ropes are racked and smoked for about two to eight hours. Since the starting mixtures are high in moisture, after smoking, the product yields typically range from about 40% to 45%. The resulting pet jerky products are then cut into pieces and packaged for room temperature distribution. The products are chewy, low intermediate moisture and relatively dense compared to conventional dry dog foods or even to semi-moist pet foods. These products exhibit shelf stability due to low A.sub.w 's resulting from the reduced moisture content as the products dry during the smoking/drying step. Better meat treats are characterized by shelf stability, high meat content (i.e., 60% to 80%), high cost, and good texture, i.e., soft and pliable yet cohesive.
While popular, pet jerky meat treats are not without disadvantages. The principle disadvantage with pet jerky treats is their relatively high cost. Their high cost results primarily from their high ingredient cost, the reduction in yields due to moisture loss and from their labor intensive, long drying (i.e., high energy consumptive) methods of preparation and in order for treats to be both shelf stable and flexible or chewy, frequently the products must be made quite thin or in relatively small pieces.
Given the state of the pet food art, there is a continuing need for new and useful pet jerky treat products of good quality and reduced cost. Surprisingly, the present invention overcomes disadvantages of the prior art and provides good quality jerky meat treats of high meat content but low cost. In its method aspect, the present invention provides simplified and inexpensive methods for preparing such products. Furthermore, the present invention provides a use for low value, underutilized animal carcass processing, waste materials and thereby converts a material characterized by difficult disposal problems into a valuable raw material.